1. Field of the Invention
The present invention relates to a substrate processing device which performs processing for a substrate (a silicon wafer).
2. Description of the Related Art
Heretofore, in semiconductor manufacturing liquid crystal device manufacturing processes, a substrate processing device has been used. The substrate processing device is a device which mounts a substrate on a holding surface of a ceramic base and performs processing such as heating for the substrate. There is also a substrate processing device which functions as a plasma generating device.
In the case of using the substrate processing device also as the plasma generating device, there are provided an RF electrode (a high-frequency electrode), and a power supply member for the RF electrode (for example, a Ni rod as a metal conductor), which supplies a high-frequency current to the RF electrode (for example, refer to Japanese Patent Laid-Open Publication No. H11-26192 published in 1999).
When a high-frequency voltage is applied to the power supply member, due to the skin effect, the current flows concentratedly through a surface of the power supply member (for example, the surface extends in a range from an outer circumferential surface of the power supply member to several-micron to several ten-micron deep), and the current hardly flows through a diametrical center of the power supply member.
Resistance of the power supply member is represented by the following equation (1). Since the current hardly flows through the diametrical center of the power supply member due to the skin effect as described above, an apparent cross sectional area S is decreased. As a result, the resistance R rises.R=L/σS  (1)
where                R: resistance;        L: length of power supply member;        σ: conductivity; and        S: cross-sectional area        
Meanwhile, the amount of heat generated by the power supply member is represented by the following equation (2). When the resistance R rises, the heat generation amount also increases.W=RI2  (2)
where                W: heat generation amount;        R: resistance; and        I: current        
As described above, when a high-frequency voltage is applied to the power supply member, there has been a problem that the amount of heat generated by the power supply member increases due to the skin effect.
Here, since many peripheral members arranged in the substrate processing device have complicated shapes, parts formed of resin, in which processability is good and electrical insulating properties are also excellent, are used as the peripheral members in many cases. However, since the peripheral members formed of resin have relatively low heat resistance, the possibility exists that the peripheral members may be damaged by the high-temperature power supply member. A specific description will be made below.
Even in the case of a heat-resistant resin said to have a high heat resistance among the resins, the heat resistant temperature thereof is approximately 250° C. Therefore, when a high-frequency current and large power of an alternating current are supplied through the power supply member to the electrode of the substrate processing device, the temperature of the power supply member reaches 250° C. or more, and there has been a possibility that the peripheral members (parts) formed of the resin are damaged.
Moreover, there is a substrate processing device including a resistance heating element, and a power supply member for the resistance heating element, which supplies a voltage to the resistance heating element, and the power supply member concerned is directly connected to the resistance heating element. Therefore, in the case of heating the substrate processing device to a high temperature, the power supply member is also heated to the high temperature due to heat transfer, and the possibility exists that the peripheral members formed of the resin are damaged.
In order to prevent such damage, it is conceivable to employ, as a material of the peripheral members, ceramics and the like which have heat resistance and which are less prone to cause thermal deformation. However, since it is difficult to process the ceramics, it is difficult to form the ceramics into the complicated shapes. Moreover, the ceramics are expensive. Therefore, it has been difficult to employ the ceramics.